Yeast has been used to leaven dough for bread and the like for, quite literally, thousands of years. The presence of yeast in a dough composition imparts a particular aroma and flavor to the finished product which is widely associated with high-quality bread, pastries and other baked goods.
In producing refrigerated doughs commercially, typically a large batch of dough is made and the dough is divided into smaller portions. These smaller portions are commonly placed in individual sealable containers for subsequent sale to consumers. In many instances, the dough portions are leavened in these containers in a process known as "proofing." The containers are designed in such a way as to allow the lid to act as a gas vent for a head space of air which is left above the unleavened dough. The dough is then leavened under controlled conditions so that it expands to fill the container and effectively seal the lid. This leavening is often continued until a positive pressure of about 15-20 psi is attained within the container, at which time the leavening action must cease. If the leavening were to continue significantly beyond this point, the pressure within the container could exceed acceptable safety limits and cause the container to rupture. These containers may then be shipped and stored for later sale and use. Such commercially produced doughs are commonly refrigerated in order to extend their shelf life; a minimum acceptable shelf life for most commercial applications is deemed to be about 90 days.
In dough compositions, the yeast culture generally continues to grow and produce carbon dioxide until the dough is baked, requiring rather precise control over the leavening conditions in order to produce a consistent product. Even at refrigeration temperatures, which generally range between about 0.degree. C. and 12.degree. C., yeast cultures in doughs remain active and continue to produce carbon dioxide. Accordingly, when yeast is used as the leavening agent in a dough, carbon dioxide pressure within a sealed storage container can relatively quickly build to a level which causes the containers to rupture or explode. In order to produce a refrigerated dough product with a shelf life of at least 90 days, dough manufacturers have therefore been effectively unable to use yeast as a leavening agent in commercial refrigerated dough products.
Dough manufacturers have been forced to replace yeast in doughs with chemical leavening agents, such as baking soda or the like. Such chemical leavening agents generally comprise a combination of a leavening acid (e.g., citric acid or glucono delta lactone (GDL)) and a leavening base (e.g., bicarbonate of soda). The acid and base portions of these leavening agents react with one another to generate carbon dioxide gas within the dough, causing the dough to increase in volume, or "rise." One of the primary advantages of such leavening agents is that their behavior is based upon a predictable chemical reaction, permitting one to readily control the volume of carbon dioxide produced to leaven the dough. Once the chemical reaction of the leavening agents has proceeded to completion, carbon dioxide production ceases.
This permits commercial dough manufacturers to produce a product with an extended shelf life without having to worry about the continuing leavening action which would occur with yeast as a leavening agent. However, it is widely agreed that the taste and texture of a dough which has been leavened with chemical leavening agents is noticeably inferior to yeast-leavened products. In order to simulate the desirable taste and aroma of yeast-leavened dough products, yeast flavoring, such as inactive pasteurized yeast cultures, is often added to the chemically leavened dough. Nonetheless, products made from such doughs still lack the characteristic flavor associated with yeast leavening. Additionally, such flavorings do not change the fact that chemically leavened refrigerated dough yields a product which has an inferior texture and a significantly lower specific volume than typical yeast-leavened products.
For these reasons, there has been a long-felt need in the field for a yeast-leavened dough product which may be refrigerated for extended periods of time. However, despite this acutely-felt need, experimenters have been unable to develop a dough composition in which yeast provides the necessary leavening action to leaven the dough and proof the storage container, yet substantially cease carbon dioxide production at refrigeration temperatures for extended storage of the dough product.